Formation behavior and microstructure of anodic films grown on MgLiY alloy, which is the most prominent super light alloy capable for easy deformation, were investigated with attention to the effects of anodizing voltage and alloying elements. The MgLiY alloy sheets were anodized at constant voltages in NaOH solution. Similar to those associated with typical pure magnesium and AZ alloys, barrier films or semi-barrier films were formed except at around 5-7V and breakdown voltages. At the latter voltages, thick porous type films were formed. Cross sectional investigation of the oxide films by using TEM combined with ultramicrotomy and depth profiles of constituent elements measured by GD-OES clearly showed that lithium was highly enriched at the outer part and yttrium enriched in the middle to inner part of the film when the film was barrier type. The ratio of barrier film thickness to anodizing voltage was as high as 4.25 nm/V relative to 1.9 nm/V of that associated with 99.95% Mg. When the film was porous type, the content of both lithium and yttrium decreased and distribution of both elements became uniform. Further, the film structure became more dense and uniform when aluminate ion was added in the electrolyte. Correlation between anodic film structure and corrosion resistance was also investigated.